Dodge ZB 2005 Service Manual page 1388

3.2 AUDIO SYSTEM
The PCI bus inputs into the radio are used for VF
dimming and for radio diagnosis with the DRBIII .
The radio is capable of displaying faults and allow-
ing certain actuation tests through the use of the
DRBIII . When attempting to perform PCI bus
diagnostics, the first step is to identify the radio in
use in the vehicle.
When trouble shooting output shorts or ''output''
error messages, the following applies:
On radios without an external amplifier, the term
output refers to the path between the radio and the
speaker. This type of circuit can be monitored all
the way through the speaker connections by the
radio assembly. When the radio displays a shorted
output DTC with this type of system, the speaker,
radio, or wiring could be at fault.
On radios with an external amplifier, the term
"output" refers to the circuit between the radio
connector and the amplifier. The radio is capable of
monitoring only this portion and can tell nothing
about the circuit between the amplifier and the
speakers. Consequently, a shorted output DTC on
this type of system would only refer to this circuit.
A faulty speaker could not cause this DTC.
3.2.1 REMOTE RADIO CONTROLS (IF
EQUIPPED)
These radios can be controlled via remote radio
switches (optional). These switches are located on
the back side of the steering wheel. They control
mode, preset, seek up, seek down, volume up and
volume down functions.
These functions are inputs to the Body Control
Module and can be read with the DRBIII under
''body computer''. The switches are a multiplexed
signal to the BCM. The radio control MUX circuit is
a 5 volt line that is pulled to ground through
different value resistors built into the switches.
This causes a voltage drop to be seen by the BCM
and it sends a specific message to the radio on the
PCI Bus circuit. The radio then responses to the
message.
This circuit is fairly simple to troubleshoot. The
circuit must be complete from the switches in the
steering wheel to the BCM. The ground must be
complete so that the switches can cause the voltage
drop for the BCM to see. The circuit passes through
the clockspring so continuity through this device
must be verified.
3.3 BODY CONTROL MODULE
The body control module (BCM) supplies vehicle
occupants with visual and audible information and
controls various vehicle functions. To provide and
GENERAL INFORMATION
receive information, the module is interfaced to the
vehicle's serial bus communications network (PCI).
This network consists of the powertrain control
module (PCM), the mechanical instrument cluster
(MIC), BCM, the airbag control module (ACM), the
controller antilock brake (CAB), the HVAC control
module and the radio. The RKE and Tire Pressure
Monitor modules have serial links to the BCM. The
BCM is operational when battery power is supplied
to module and not in Battery Save Mode. The BCM
provides the following features:
•
Vehicle Entry
• Virtual lock
• Automatic Door Lock
•
Exterior lighting
•
Interior Lighting (Courtesy/Reading Lamps)
• Tire pressure monitor input
• Horn
•
Power Windows
•
Vehicle Theft
• Battery Save Feature
• Door Lock Inhibit
•
Battery Protection
The BCM will automatically turn off all exterior
lamps after 3 minutes and all interior lamps after
15 minutes after the ignition is turned off, if they
are not turned off by the driver.
•
Chime Driver
• BCM Diagnostic Reporting
• Headlamp Time Delay
• Illuminated Entry
•
Fade to Off
This feature dims the interior lighting (courtesy
lamps) gradually if the BCM does not receive any
new inputs that would cause the interior lamps to
remain on.
•
Remote Radio Controls (if equipped)
• PWM Instrument Panel Dimming (HVAC and
radio)
• Bus Message Panel Dimming to Cluster, HVAC &
Radio
•
Door Lock Inhibit
This feature disables the door lock functions if
the key is in the ignition and either front door is
ajar. Pressing the RKE lock/unlock button under
these conditions, result in normal lock/unlock
activation.
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